{
  "bibcode": "2021GCN.29743....1P",
  "body": "K. L. Page (U Leicester), S. D. Barthelmy (GSFC),\nF. E. Marshall (NASA/GSFC) and D. M. Palmer (LANL) report on behalf of\nthe Neil Gehrels Swift Observatory Team:\n\nBAT has triggered on a new GRB 210402A (Trigger #1040123) causing \nSwift to slew to the location and make follow-up observations.  \nDue to a ground pass at the time of the GRB, no precise trigger \ntime, location, or light curve data is immediately available. \nThese details will be given in a later circular. \n\nWe note that Fermi triggered on a GRB at around the same time at a \nconsistent location (Fermi Trigger #639093861) confirming its GRB status. \n\nUsing promptly downlinked data we find a bright, uncatalogued X-ray\nsource located at RA, Dec 198.25866, 44.51291 which is equivalent to:\n   RA(J2000)  = 13h 13m 02.08s\n   Dec(J2000) = +44d 30' 46.5\"\nwith an uncertainty of 3.5 arcseconds (radius, 90% containment). This\nposition may be improved as more data are received; the latest position\nis available at https://www.swift.ac.uk/sper. \n\nA power-law fit to a spectrum formed from promptly downlinked event\ndata gives a column density consistent with the Galactic value of 1.51\nx 10^20 cm^-2 (Willingale et al. 2013). \n\nThe initial flux in the 2.5 s image was 1.31e-08 erg cm^-2 s^-1 (0.2-10\nkeV). \n\nUVOT took a finding chart exposure of nominal 150 seconds with the\nWhite  filter. No credible afterglow candidate has  been found in the\ninitial data products. The 2.7'x2.7' sub-image covers 100% of  the XRT\nerror circle. The typical 3-sigma upper limit has been about 19.6 mag. \nNo correction has been made for the extinction in the Milky Way. \n\nBurst Advocate for this burst is K. L. Page (klp5 AT leicester.ac.uk). \nPlease contact the BA by email if you require additional information\nregarding Swift followup of this burst. In extremely urgent cases, after\ntrying the Burst Advocate, you can contact the Swift PI by phone (see\nSwift TOO web site for information: http://www.swift.psu.edu/)",
  "circularId": 29743,
  "createdOn": 1617402612000,
  "email": "scott@milkyway.gsfc.nasa.gov",
  "subject": "GRB 210402A: Swift detection of a burst",
  "submitter": "Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>",
  "eventId": "GRB 210402A"
}